Loop currents in AV3Sb5 kagome metals: Multipolar and toroidal magnetic orders
Loop currents in AV3Sb5 kagome metals: Multipolar and toroidal magnetic orders
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DOI：
10.1103/physrevb.106.144504
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发表时间：
2022-10-12
影响因子：
3.7
通讯作者：
Fernandes, Rafael M.
中科院分区：
文献类型：
--
作者：
Christensen, Morten H.;Birol, Turan;Fernandes, Rafael M.
对最近发现的基于钒的Kagome金属的实验表明，它们的电荷有序状态不仅显示出键扭曲，特征是“真正的”电荷密度波(RCDW)，而且还有时间反转对称性破坏，典型的回路电流由“想象的”电荷密度波(ICDW)描述。在这里，我们结合密度泛函理论、群论和唯象模型研究了AV3Sb5电子结构中低能van Hove奇点之间相互作用产生的复电荷有序态。我们发现了两大类混合的iCDW-rCDW构型：三Q iCDW，三Q rCDW序，称为3Q-3Q，以及双Q iCDW，单Q rCDW序，称为2Q-1Q。此外，我们确定了七种不同类型的iCDW有序，它们源于费米能级上下两对van Hove奇点的不同的钒轨道结构和Kagome子晶格结构。2q-1q态引发的正交扭曲破坏了Kagome晶格的三重旋转对称性，而3q-3q态诱导了各种辅助的均匀磁序，从传统的铁磁性到磁八极、磁环甚至磁单极序。我们发现这些奇特的有序显示出独特的磁致伸缩、磁电和磁电伸缩性质，可以通过实验来检测这些化合物中实现了哪种iCDW态。我们简要讨论了电荷有序的平面外调制的影响，以及这些复杂的电荷有序态与超导电性之间的相互作用。
Experiments in the recently discovered vanadium-based kagome metals have suggested that their charge -ordered state displays not only bond distortions, characteristic of a "real" charge density wave (rCDW), but also time-reversal symmetry breaking, typical of loop currents described by an "imaginary" charge density wave (iCDW). Here, we combine density-functional theory, group theory, and phenomenological modeling to investigate the complex charge-ordered states that arise from interactions between the low-energy van Hove singularities present in the electronic structure of AV3Sb5. We find two broad classes of mixed iCDW-rCDW configurations: triple -Q iCDW, triple -Q rCDW order, dubbed 3Q-3Q, and double -Q iCDW, single -Q rCDW order, dubbed 2Q-1Q. Moreover, we identify seven different types of iCDW order, stemming from the different vanadium-orbital and kagome-sublattice structures of the two pairs of van Hove singularities present above and below the Fermi level. While the 2Q-1Q states trigger an orthorhombic distortion that breaks the threefold rotational symmetry of the kagome lattice, the 3Q-3Q states induce various types of subsidiary uniform magnetic orders, from conventional ferromagnetism to magnetic octupolar, magnetic toroidal, and even magnetic monopolar order. We show that these exotic orders display unique magnetostriction, magnetoelectric, and magnetoelectrostriction properties that can be probed experimentally to identify which iCDW state is realized in these compounds. We briefly discuss the impact of an out-of-plane modulation of the charge order and the interplay between these complex charge-ordered states and superconductivity.